1. Field
Exemplary embodiments relate to a fuel reformer included in a fuel processor, and more particularly, to a fuel reformer which includes a reformer flame blocking member and a reforming pipe having corrugations that contribute to improving the durability and operating reliability of a fuel cell system.
2. Description of the Related Art
A fuel cell system is a power generation system that directly converts the chemical energy of hydrogen and oxygen contained in a hydrocarbon-based material, such as methanol, ethanol, or natural gas, into electric energy. A fuel cell system using hydrogen gas includes a fuel cell stack and a fuel processor. The fuel cell stack has a structure in which several to tens of unit cells, each including a membrane electrode assembly (MEA) and a separator, are stacked.
FIG. 1 is a schematic block diagram of a fuel cell system. Referring to FIG. 1, a fuel, containing hydrogen, is reformed to hydrogen gas in a fuel processor, and the hydrogen gas is supplied to a fuel cell stack. The fuel cell stack receives the hydrogen gas, the hydrogen gas and oxygen electrochemically react in the fuel cell stack, and the fuel cell stack generates electric energy therefrom.
The fuel processor includes a desulfurizer and a hydrogen generator, and the hydrogen generator includes a reformer, a shift reactor, and a CO remover. The desulfurizer removes sulfur from the fuel so that a catalyst of the reformer and the shift reactor is not poisoned by a sulfur compound.
The reformer generates hydrogen gas, carbon dioxide, and carbon monoxide from hydrocarbons. However, since the carbon monoxide poisons the catalyst used in an electrode of the fuel cell stack, the hydrogen gas generated in the reformer is supplied to the fuel cell stack after the carbon monoxide is removed from the hydrogen gas through the shift reactor and the CO remover. The hydrogen gas that passes through the shift reactor has an amount of carbon monoxide more than about 10 ppm to hundreds of ppm. The CO remover reduces the amount of the carbon monoxide from the hydrogen gas that passed through the shift reactor to less than 10 ppm.
FIG. 2 is a schematic cross-sectional view of a fuel reformer 10. Referring to FIG. 2, the fuel reformer 10 includes a burner 15 which forms a flame 25 in a combustion chamber 11 inside a reforming pipe 22 including a reforming catalyst layer 20. If a combustion fuel, which is a mixture of gas of methane (CH4) and air, is ignited when the combustion fuel is ejected to the combustion chamber 11 via the burner 15, the flame 25 is generated in the combustion chamber 11, and the reforming catalyst layer 20 is heated, thereby generating a hydrogen generation reaction.
Also, since the fuel reformer 10 is operated at a high temperature, the burner 15 is used to supply heat necessary for the hydrogen generation reaction with combustion heat of the fuel in order to increase the temperature of the fuel reformer 10. However, if heat is directly supplied to the chamber 11, the flame 25 directly touches the reforming pipe 22, and the reforming catalyst 20 may be locally overheated. Also, the flame 25 directly touches a surface of the reforming pipe 22, and thus a hot spot is generated on the reforming pipe 22, which reduces the durability of the fuel reformer 10 due to damage in the material and structure of the fuel reformer 10.